Due to advances in technology, it has become increasingly easy to generate content. For example, desktop publishing software allows graphics artists, designers, office workers, students, business owners, etc. to produce high quality photographs, posters, web pages, slide presentations, reports, and even videos. However, the ease with which one can create content also has led to increased public concerns over unauthorized use of content and related legal issues, such as copyright violations, privacy issues, etc. This in turn has led to development of a wide-range of techniques for protecting content-use rights.